.left_background {
  z-index: -1;
  position: absolute;
  top: 50%;
  left: 0;
  width: 40%;
  height: 100%;
  // background: url(../../assets/rhineLab.png) top/cover no-repeat;
  background-position: top;
  background-size: cover;
  background-repeat: no-repeat;
  mask: linear-gradient(90deg, #fff, transparent 100%);
  transform: translateY(-50%);
  opacity: 0;
  transition: opacity .3s;
}

.startProcess {
  .left_background {
    opacity: 0.25;
  }
}